Springs
Page 17
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Which Absorb Side Shocks.
TTY-SEVEN miles an hour over a very rough road in a large, solid-tyred coach, and without any feeling of discomfort or danger, is something out of the ordinary, for with normal springs we have found that, in such circumstances, a coach is inclined to bounce and sway to an alarming extent. The secret of this smooth running lies. in the special form of springing applied to the vehicle which we tested, this including the jumping of kerbstones at high speed; this springing is the Gattie, developed by Gattie Springs, Ltd., as the result of . experiments
carried on for several years. .
In the Gattie scheme use is made of rectangular-sectioned coil springs, completely enclosed in an ahiminiiim casing and connected to the vertical plunger, which takes the load, through a -system of toggle levers so arranged that the spring effect is automatically increased under load, and, consequently, a damping-out effect is obtained.
Only vertical shocks are taken by the coil springs, for the plunger for each wheel has a flat base, which rests on a chilled-iron hemisphere floating in 'a cup attached to the axle of the vehicle. Any shocks other than vertiml are taken, in the case of the front axle, by special plate springs stretching from the dumbIrons to the axle, and so arranged that they give the effect of a parallel-link motion, which prevents axle twist ; they are also curved to resist direct blows. Suitable stops prevent undue sideways movement of the whole axle, but it will be appreciated that the major portion of any side shock has been absorbed by the springs before contact can be made with these stops.
In the ease of the rear axle, Hotchkiss drive cannot be employed, as vertical springs for the side stresses are utilized, the ends of these, passing between rollers which serve •to give the effect of spring shortening, and consequent stiffening, as the load is increased. The vertical component is again absorbed by the enclosed coil strings.
The setting of the toggles is such that at full lead the leverage is 1 to 1, and at no load—with the vehicle running light —3 to 1.
It is claimed that this springing has a great effect on both speed an petrol consumption, for the wheels are kept in more intimate contact with the ground, and practically no rotary skidding of those which take the drive can occur.
The cushioning of side blows will, it is considered, have a great effect, on chassis construction, as heavy. wheels. etc:, are not required, and -Mr. A. W. Gattie claims that he will be able to reduce the weight of a four-toe chassis by some 15 cwt. It is also believed that side skidding will be greatly diminished.